How many elliptical orbits are added by Sommerfeld in third Bohr's orbit? What was the purpose of adding these elliptical orbits ?

Explanation

Sommerfeld added two elliptical orbits to Bohr's third orbit.
Purpose of adding elliptical orbits :
1) Bohr's model failed to account for splitting of line spectra and line spectrum.
2) In an attempt to account for the structure of line spectrum, Sommerfeld modified Bohr's atomic model by adding elliptical orbits.